A girl who works in your lab basically asks you for Midol ("painkiller that's stronger than Advil"), and you don't actually ever carry around Midol because you don't have a uterus.
There's a lot of stuff in my life that's like this, actually. Although I'm not necessarily living in stealth, I've learned to keep my trans status to myself when possible, because as soon as you disclose to someone they [more often than not] start acting really weird around you for no reason. So like when I was living with a bunch of other girls, I actually used to keep a box of tampons handy just in case one of them ever ran out and asked me for some. I guess now I should carry some emergency Midol around with me from now on :P
(fun side note: although I don't get cramps, I do get some PMS-like symptoms because of the way my estrogen levels fluctuate with my injection schedule. Usually Advil can take care of what painkillers are able to fix, though).